Potential aldehyde/catecholamine condensation reactions, which produce behaviorally active tetrahydroisoquinoline alkaloids, are being studied in rat brain, heart and adrenal tissues under various conditions during alcohol or acetaldehyde metabolism. The alkaloid products are under investigation as in vivo and in vitro inhibitors of CA biosynthetic enzymes. The urines from human alcoholics during detoxification are being examined by gas chromatography and high pressure liquid chromatography for the possible presence of several of the catecholamine-derived tetrahydroisoquinolines.